It is hypothesized that high resting muscle tension is associated with insensitivity or imprecision in subjective assessment of tension. High resting muscle tension may occur in those who are unable to assess tension variations and therefore unable to make appropriate adjustments. Estimates of sensitivity and precision are obtained from verbal reports of tension change from one short observation interval to another and from the psychophysical function relating subjective magnitude to hand dynamometer pressure. In addition, the latter function is examined within individuals and decomposed into the relationship between subjective magnitude and EMG and between EMG and dynamometer pressure. This may permit localization of the nonlinearity of the psychophysical function relating subjective magnitudes and dynamometer pressure.